Radiotherapy: fractionation principles: practice question

A Radiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Radiology · Radiotherapy: fractionation principles

Sample item

The rationale for fractionating radiotherapy into multiple small doses includes all of the following EXCEPT:

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Increased tumour hypoxia between fractions

The classic four Rs are repair, reassortment (redistribution), reoxygenation and repopulation (a fifth, radiosensitivity, is sometimes added). Fractionation lets normal tissues repair while tumour cells reoxygenate and redistribute. Increased hypoxia would reduce, not support, the benefit.

Option by option

  • A. Increased tumour hypoxia between fractions (correct)

    Correct. Hypoxia is not a benefit of fractionation; reoxygenation is.

  • B. Reoxygenation of hypoxic tumour cells

    Reoxygenation is one of the four Rs.

  • C. Redistribution of cells into sensitive phases

    Redistribution is one of the four Rs.

  • D. Repair of sublethal damage in normal tissue

    Repair favours normal tissue and is a rationale.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is A, Increased tumour hypoxia between fractions. The classic four Rs are repair, reassortment (redistribution), reoxygenation and repopulation (a fifth, radiosensitivity, is sometimes added).

Why is "Reoxygenation of hypoxic tumour cells" not the answer?

Reoxygenation is one of the four Rs.

Why is "Redistribution of cells into sensitive phases" not the answer?

Redistribution is one of the four Rs.

Why is "Repair of sublethal damage in normal tissue" not the answer?

Repair favours normal tissue and is a rationale.

What concept does this question test?

It tests Radiotherapy: fractionation principles in Radiology. Fractionation lets normal tissues repair while tumour cells reoxygenate and redistribute. Increased hypoxia would reduce, not support, the benefit.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Radiotherapy: fractionation principles?

Learn signs with the image, and the disease they point to. Then use the flashcards and the other Radiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.